Simultaneous Adsorption of Gaseous Hg and Hg(II) by Regenerable Monolithic FeMoS/TiO: Mechanism and its Application in the Centralized Control of Hg Pollution in Coal-Fired Flue Gas.

FeMoS/TiO was investigated as a regenerable sorbent to simultaneously adsorb Hg and Hg(II) from coal-fired flue gas for the centralized control of Hg pollution discharged from coal-fired power plants. The performance of FeMoS/TiO for Hg(II) and/or Hg adsorption was evaluated on a fixed-bed reactor at 80 C, and the mutual interference between Hg adsorption and Hg(II) adsorption was analyzed using individual adsorption, simultaneous adsorption, and two-stage adsorption. FeMoS/TiO displayed an excellent capacity for individual Hg adsorption (41.8 mg g) and a moderate capacity for individual Hg(II) adsorption (0.48 mg g). Two types of adsorption sites were present on FeMoS/TiO for gaseous Hg adsorption (S and FeS/MoS sites). X-ray photoelectron spectroscope and kinetic analyses demonstrated that Hg and Hg(II) could adsorb onto S sites, whereas only Hg was adsorbed onto FeS/MoS sites. As Hg competed with Hg(II) for the S sites, the amount of Hg(II) adsorbed slightly decreased by 16% in the presence of Hg. However, Hg adsorption onto the FeS/MoS sites predominated over the Hg adsorption onto FeMoS/TiO and it was not inhibited in the presence of Hg(II). Therefore, the amount of Hg adsorbed on FeMoS/TiO was only decreased by 2% in the presence of Hg(II).